content: /*
   * Copyright 2016-present David Karnok
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *     http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  package hu.akarnokd.rxjava3.subjects;
  
  import java.util.Objects;
  
  import io.reactivex.rxjava3.annotations.*;
  import io.reactivex.rxjava3.subjects.Subject;
  
  /**
   * Utility methods to work with RxJava 2 Subjects.
   * @since 0.18.2
   */
  public final class Subjects {
      /** Utility class. */
      private Subjects() {
          throw new IllegalStateException("No instances!");
      }
  
      /**
       * Wraps a Subject and makes sure if all observers dispose
       * their disposables, the upstream's Disposable gets disposed as well.
       * <p>
       * This operator is similar to {@link io.reactivex.rxjava3.observables.ConnectableObservable#refCount()}
       * except the first Observer doesn't trigger any sort of connection; that happens
       * when the resulting Subject is subscribed to an Observable manually.
       * @param <T> the input and output value type
       * @param subject the subject to wrap, not null
       * @return the wrapped and reference-counted Subject
       * @since 2.1.8 - experimental
       */
      @NonNull
      @CheckReturnValue
      public static <T> Subject<T> refCount(Subject<T> subject) {
          if (subject instanceof RefCountSubject) {
              return subject;
          }
          return new RefCountSubject<>(Objects.requireNonNull(subject, "subject is null"));
      }
  }
  